This invention relates generally to the marking of electrical wires for identification purposes. This invention relates more particularly to the use of heat shrinkable tubing onto which identifications are permanently placed, and which are then permanently installed on electrical wires, the entire operation being accomplished at the job site.
Within the electrical industry, complicated electrical controls, power wiring and wiring to inputs and outputs of complicated programmable logic controllers for the controlling of machinery have made it necessary to develop a method of identifying wires throughout the electrical system. Without this wire identification, the troubleshooting and repairing often associated with electrical equipment would be practically impossible, as well as extremely time consuming.
The most common method employed today utilizes various types of numbers which come in a booklet form. The electrician peels off a number or a series of numbers which have adhesive backings thereon, and wraps these numbers around the wires for identification. This method is quite time consuming, and as the markers lose their adhesive quality over a period of time due to heat or oily conditions found on job sites, the markers have a tendency to fall off. The wires are then left with no identification, which can present problems as discussed above.
Within the last few years, various methods have been devised utilizing a heat shrinkable sleeve that is partially preshrunk on an assembly for the purpose of flattening the sleeve, as disclosed in Evans, U.S. Pat. No. 4,032,010 and in Gandolfo, U.S. Pat. No. 4,586,610. Once flattened, these sleeves may be marked by a computer or typewriter and then sent to the job site to be applied by the electrician on the job. This method is very tedious as there are often thousands of wires to be marked throughout the duration of the job, and locating the proper marker sleeve needed for each individual wire is very time consuming, and can thus become impractical. Also, sleeves are sometimes lost or damaged, and a replacement can not be readily made. The electrician must request that a new marker sleeve be made, and then wait until that new sleeve is delivered. A great deal of time can be wasted in this manner.
Accordingly, this invention provides a flat assembly analogous to a clipboard which lends support to the hand for the purpose of handwriting with a permanent marking ink pen on a flattened tubular heat shrinkable sleeve. The tubular sleeve is flattened by forcing it with a minimum amount of force onto a metal tab extending from the assembly. The sleeve is marked and then removed from the extension with a minimum amount of pulling force, at which time the sleeve recovers its original tubular form. It is then slipped onto the wire and heat shrunk firmly to the conductors for a permanent installation. This operation is accomplished entirely at the job site, without any of the aforementioned problems which have been associated with the marking of wires in the past.